Ferritic coiling of wire or bar steel

Abstract

A method of coiling or placing bar steel or wire in coils, wherein the rolling stock is reeled from rolling heat in a basket or is placed by a coiler in the form of coils onto a conveyor and is collected at the end of the conveyor over a mandrel into a coil, wherein the rolling stock is cooled during coiling and the rolling stock is further cooled after the coiling process or the formation of coils. Cooling of the rolling stock from rolling heat prior to coiling into the transformation range characterized by the Ar 3 line or Ar 1 line of the transformation time-temperature diagram corresponding to the type of steel to be cooled is extended, such that, depending on the type of steel, the rolling stock is transformed immediately after cooling prior to, during or after coiling, uniformly over the entire length and entire cross-section thereof essentially isothermally from the austenite phase into the ferrite phase or pearlite phase and, as required, into the bainite phase.

We claim: 
     
       1. In a method of coiling rolling stock in the form of bar steel or wire or placing the rolling stock in windings, wherein the rolling stock is reeled from rolling heat in a basket or is placed by a coiler in the form of windings on a conveyor means and is collected at an end of the conveyor means over a mandrel into a coil, wherein the rolling stock is cooled during reeling or placing into windings and is further cooled after reeling or placing into windings, the improvement comprising carrying out cooling of the rolling stock from rolling heat to about 650° C. prior to reeling the rolling stock or placing the rolling stock into windings, such that, depending on the type of steel, the rolling stock is transformed immediately after cooling prior to, during or after reeling or placing into coils, uniformly over the entire length and entire cross-section thereof essentially isothermally from the austenite phase into the ferrite phase or pearlite phase and, as required, into the bainite phase. 
     
     
       2. The method according to claim 1, comprising, in types of steel which transform only after coiling, preventing further cooling by using cover plates or holding hoods, so that the transformation takes places essentially isothermally. 
     
     
       3. The method according to claim 1, comprising carrying out cooling of the rolling stock such that the surface of the rolling stock is not undercooled and reaches the range of martensite formation. 
     
     
       4. The method according to claim 1, comprising carrying out cooling of the rolling stock such that the transformation into the ferrite phase or pearlite phase is completely concluded prior to the coiling process, whereby the low deformation resistance of the ferrite phase or pearlite phase due to the cubic body centered crystal lattice of these phases can be utilized during coiling. 
     
     
       5. The method according to claim 1, comprising cooling the rolling stock to the desired transformation range in a controllable cooling stretch. 
     
     
       6. The method according to claim 5, comprising cooling the rolling stock in a water cooling stretch. 
     
     
       7. The method according to claim 1, comprising, after transformation has been completed and coiling has been carried out, subjecting the rolling stock to forced cooling to binding temperature.